Math Problem Statement

A is a cylinder of radius and height B is a sphere with radius .

Sphere 's volume is 5 times as big as the volume of cylinder .

Find an expression for in terms of .

Solution

We are given that the volume of the sphere BB is 5 times the volume of the cylinder AA. We need to find an expression for the radius rr of the sphere in terms of the radius RR and height HH of the cylinder.

Step 1: Write the volume of the cylinder AA

The formula for the volume of a cylinder is: Vcylinder=πR2HV_{\text{cylinder}} = \pi R^2 H where RR is the radius of the base of the cylinder, and HH is the height of the cylinder.

Step 2: Write the volume of the sphere BB

The formula for the volume of a sphere is: Vsphere=43πr3V_{\text{sphere}} = \frac{4}{3} \pi r^3 where rr is the radius of the sphere.

Step 3: Relate the volumes

We are told that the volume of the sphere is 5 times the volume of the cylinder. Therefore, we have the equation: Vsphere=5×VcylinderV_{\text{sphere}} = 5 \times V_{\text{cylinder}} Substituting the formulas for the volumes: 43πr3=5×πR2H\frac{4}{3} \pi r^3 = 5 \times \pi R^2 H

Step 4: Simplify the equation

We can divide both sides of the equation by π\pi to eliminate it: 43r3=5R2H\frac{4}{3} r^3 = 5 R^2 H

Step 5: Solve for r3r^3

Multiply both sides by 34\frac{3}{4} to isolate r3r^3: r3=154R2Hr^3 = \frac{15}{4} R^2 H

Step 6: Solve for rr

Take the cube root of both sides to solve for rr: r=(154R2H)13r = \left( \frac{15}{4} R^2 H \right)^{\frac{1}{3}}

Thus, the expression for the radius rr of the sphere in terms of the radius RR and height HH of the cylinder is: r=(154R2H)13r = \left( \frac{15}{4} R^2 H \right)^{\frac{1}{3}}

Do you want more details or have any questions?

5 Related Questions:

  1. How would the expression change if the sphere’s volume was 3 times that of the cylinder?
  2. What is the volume of the sphere if R=2R = 2 and H=3H = 3?
  3. How does the volume of the cylinder change if both RR and HH are doubled?
  4. Can you find the surface area of the cylinder in terms of RR and HH?
  5. How does the relationship change if the height of the cylinder is a function of its radius, say H=2RH = 2R?

Tip:

When dealing with volumes of 3D shapes, always make sure to pay attention to units. Using consistent units across all measurements will help avoid mistakes in calculations.

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Math Problem Analysis

Mathematical Concepts

Geometry
Volume of 3D Shapes
Algebra

Formulas

Volume of a cylinder: V_cylinder = πR^2H
Volume of a sphere: V_sphere = (4/3)πr^3
Relationship: V_sphere = 5 * V_cylinder

Theorems

Cube root theorem

Suitable Grade Level

Grades 10-12